Using an ultrasound technique serial measurements of ventricular size in high risk pre-term infants with respiratory distress or neonatal hypoxemia will be compared with similar measurements in low risk pre-term infants who are stable. An A scan mode using portable equipment will be the primary ultrasound screening technique. A real-time B scan mode will be obtained on all subjects at intervals of 7 to 14 days. ACTA scans (computer brain scans) will be obtained to validate the ultrasound measurements in all subjects with evidence of abnormally enlarging ventricles. Intracranial pressure will be measured with a pressure transducer applied to the anterior fontanelle, which is a non-invasive technique. The rate of increase in ventricular size will be calculated every 10 days. Intracranial pressures and head circumference measurements will be correlated with the ventricular size measurements. The width of the cortical mantle of each hemisphere at mid frontal, mid parietal and mid occipital areas, and the ventricular volumes will be calculated from the ultrasound B scans. All appropriate clinical studies including spinal fluid examination will be obtained whenever indicated. Thus, this research is designed (1) to determine in high and low risk pre-term infants the incidence of hydrocephalus (especially post-hemorrhagic); (2) to compare the growth rate of the cortical mantle in high risk to that of low risk pre-term infants; (3) to correlate rate of ventricular enlargement with intracranial pressure in pre-term infants; (4) to develop safe and non-invasive techniques which detect intracranial hemorrhage, hydrocephalus and brain growth in high risk preterm infants at the earliest stage of abnormality.